The present invention relates to a gas insulated high or ultrahigh voltage cable for transmitting heavy currents, and being comprised of an inner conductor for conducting the current and an outer, tubular metal jacket held coaxially to the inner conductor in spaced-apart relationship thereto.
Transporting large quantities of electrical energy, particularly in densely populated areas, pose difficulties to an increasing extent in that the heretofore used cable and conductors are no longer sufficient. In addition to the currently developed cryogenic cable, a recent development has lead to the use of so-called gas insulated electrical cable. These cable are comprised essentially of an inner conductor for conducting the current, a spacer construction, and an outer tubular metal jacket, whereby the space between inner tube and outer tube is filled, e.g., with an SF.sub.6 gas.
Two systems have been suggested for actual use in practice; one system is characterized by the use of rigid inner and outer conductors in tubular configuration, which the other system provides for the use of flexible metallic construction parts. Rigid tube systems require that a length of a cable be installed at a construction site through interconnection of relatively short individual lengths. On the other hand, flexible systems can be handled just like the usual cables i.e., following manufacturing they are reeled on cable drums and unreeled therefrom during installation.
Both systems pose difficulties due to the relatively large diameter of the inner conductor. Such a large diameter is required for the conduction of heavy currents. Large cross-sections here lead to correspondng large cross-sections of the copper which, in turn, leads to a large weight and high stiffness of the inner conductor. Aside from the reduced degree of bendability, the spacer construction is detrimentally affected by that large weight.